Phylogenetic structure of alpine steppe plant communities along a precipitation and temperature gradient on the Tibetan Plateau

Abstract

Exploring plant community phylogenetic structure along precipitation and temperature gradients can facilitate the study of mechanisms governing community assembly. Herein, we assessed the phylogenetic structure of alpine steppe plant communities along a precipitation and temperature gradient in Xigaze, Naqu and Ali on the Tibetan Plateau. We found that alpine steppe plant communities were generally phylogenetically clustered on both small (3 m2) and intermediate (1000 m2) scales. We found that mean annual precipitation (MAP), rather than mean annual temperature (MAT), influenced plant species richness and phylogenetic diversity on an intermediate scale. In contrast, MAT, rather than MAP, influenced the phylogenetic structure of plant communities on an intermediate scale such that higher MAT was associated with greater plant community clustering. Additionally, no changes in phylogenetic structure were observed across scales (3 m2 vs 1000 m2). In summary, precipitation is an important regulator of plant diversity, whereas temperature is a key factor that influences the phylogenetic structure of plant communities on the Tibetan Plateau. Our data offer new insights that may better guide current understanding regarding community assembly mechanisms in alpine steppe ecosystems on the Tibetan Plateau faced with global climate change.